Re: [PATCH 2/5] bitops: compile time optimization for hweight_long(CONSTANT)
From: Borislav Petkov <hidden>
Date: 2010-02-18 06:19:23
Also in:
linux-kbuild, lkml
Subsystem:
kernel build + files below scripts/ (unless maintained elsewhere), library code, the rest · Maintainers:
Nathan Chancellor, Nicolas Schier, Andrew Morton, Linus Torvalds
On Wed, Feb 17, 2010 at 06:39:13PM +0100, Michal Marek wrote:
It wouldn't work actually, because such variable would then apply to all
hweight.o targets in the tree. But another way would be:
arch/x86/Kconfig
config ARCH_HWEIGHT_CFLAGS
string
default "..." if X86_32
default "..." if X86_64
lib/Makefile
CFLAGS_hweight.o = $(CONFIG_ARCH_HWEIGHT_CFLAGS)Yep, this works, albeit with a small adjustment since CONFIG_ARCH_HWEIGHT_CFLAGS is quoted in the Kconfig and the quotes appear in the $(CC) call like this: gcc -Wp,-MD,lib/.hweight.o.d ... "-fcall-saved-ecx..." which I fixed like this (idea reused from the make manual): --- source "init/Kconfig"
diff --git a/lib/Makefile b/lib/Makefile
index 3b0b4a6..e2ad17c 100644
--- a/lib/Makefile
+++ b/lib/Makefile@@ -39,7 +39,10 @@ lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o lib-$(CONFIG_GENERIC_FIND_FIRST_BIT) += find_next_bit.o lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o obj-$(CONFIG_GENERIC_FIND_LAST_BIT) += find_last_bit.o + +CFLAGS_hweight.o = $(subst $(quote),,$(CONFIG_ARCH_HWEIGHT_CFLAGS)) obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o + obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o obj-$(CONFIG_DEBUG_LIST) += list_debug.o
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index f9bdf26..cbcd654 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib@@ -245,3 +245,7 @@ quiet_cmd_lzo = LZO $@ cmd_lzo = (cat $(filter-out FORCE,$^) | \ lzop -9 && $(call size_append, $(filter-out FORCE,$^))) > $@ || \ (rm -f $@ ; false) + +# misc stuff +# --------------------------------------------------------------------------- +quote:="
I'm open for better suggestions though.
--
Regards/Gruss,
Boris.